I keep my sprayers in the dark (inside cabinet) so nothing grows on water kept away from live bearing sunlight. Could it be you are overdosing water conditioner and that is creating the muck?

If using distilled or de-ionized water for misting; you have to avoid the frogs since it's not good for them. For misting the frogs use tap or filtered water treated with a water conditioner. Spring water (if really from spring) is normally safe to use as is. Good luck !